Toast & grind spices: Preheat a dry skillet on medium. Toast peppercorns and fennel seeds for 1-2 minutes until fragrant. Grind to a powder while hot.

Coat fish: In a bowl, combine the ground spices, smoked paprika, chilli flakes, nutmeg, sugar, and salt. Add the fish cubes and stir gently until evenly coated.

Cook pasta: Boil 3 litres of water with salt. Cook pasta according to package directions minus 1 minute. Reserve 1 1/2 cups of pasta water before draining.

Make the ragu: Heat olive oil in the same skillet over medium-high heat. Add the coated fish and cook for 2 minutes, stirring. Stir in tomato paste and simmer for 5 minutes. Add 1 cup of reserved pasta water and simmer for 2 more minutes.

Toss pasta: Add the drained pasta to the skillet. Toss for 1 minute until the pasta is well-coated with the sauce and fish flakes.

Serve immediately: Divide the pasta and ragu between bowls. Garnish if desired.